If you end up marrying the person you are now on a first date with, you will at some point have to talk about money. 

You know, paying the electric bill and saving up to send the kids to college, and all that romantic stuff.

But right now? There's no need to start drawing up a plan for splitting the bill for drinks or appetizers or whatever you ordered. 

In fact, according to relationship expert Andrea Syrtash, author of "It's Okay to Sleep With Him on the First Date," it's best to avoid talking explicitly about who's going to pay, in order to avoid exacerbating the awkwardness in this already uncomfortable situation. 

In general, Syrtash believes that whoever initiated the date should pay. The other person should accept graciously.

Interestingly, among her clients, she's noticed that most women who date men do still expect the man to pay.

If you expect the other person to pay but you're planning the date, "be respectful," Syrtash said. Try to pick a place that isn't so expensive so you won't feel guilty when your date foots the bill. She suggested arranging a date over happy hour drinks.

When the bill arrives, even if you expect the other person to pay, you should still offer to pay. Otherwise, Syrtash said, it's "kind of rude."

Know that your date might agree to split the cost — even if you weren't being entirely sincere when you offered.  If that's not what you're looking for in a partner, then it's good to know now that it's not a great match.

And if your date does end up paying, Syrtash said, make sure to say, "Thanks again and nice to meet you"— even if you weren't feeling a romantic connection.

SEE ALSO: Here's exactly what to say in 10 of the most awkward moments you'll have in a new relationship

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NOW WATCH: What you should talk about on a first date, according to research

Online dating can feel doomed from the start.

Showcasing your best qualities in the real world can be tough enough; but online you're expected to highlight them solely through a few paragraphs and pictures. What could go wrong?

Grant Langston, CEO of the online-dating site eHarmony, recently spoke with Business Insider about the biggest mistakes people make in online dating — and how they can correct them.

1. Playing it safe — and coming off boring

Years of online matchmaking have taught Langston that too many people who are new to online dating (and even some who've been in the game a while) are deathly afraid of being perceived as weird. As a result, they build profiles that are downright boring.

It's not interesting to write "I like movies" in your profile, he says. Everyone likes movies. You need something to catch other users' eye if your profile is the 20th they've seen that day.

"I need to know that you like 'The Godfather' and you've seen it fifty times, and you can quote the dialogue, and your second-favorite movie is 'Tommy Boy,'" he says. "I need details."

Not only do details make you stand out (even at the expense of coming off goofy), but juicy bits of information lead to richer interactions if you end up going on a date.

"When I say to you, 'Now, 'Tommy Boy,' why on Earth do you like that movie?' that sets you up to talk to me," Langston says, "and it's a shortcut to a better conversation."

2. Telling an entire life story in one long bio

At the other end of the spectrum are people who don't know when to stop talking about themselves. Either they think they're endlessly fascinating, or they're just too dense to realize they're oversharing.

Even if the information is interesting, Langston says, people should exercise some restraint in sharing heaps of personal stuff too quickly. Listing a few movies you're into is good. Listing your entire collection, alphabetically by director — that's excessive.

"Leave something for the date," he says. "I don't want a dissertation about your film habits."

3. Settling for a photo that isn't well-lit and in-focus

Cell-phone cameras have come a long way in the past decade, but Langston says most people are still surprisingly bad at taking a flattering photo of themselves. Men seem to be especially fine with using (what seem to be) hastily-snapped selfies taken at odd angles, he says.

"The fact is, everyone puts a big emphasis on what they see there. And if what they see there is not good, they just won't go any further," he says.

The success of dating apps like Tinder and Bumble only emphasize that point, Langston adds. People who are looking for serious relationships might say they care about a deeper connection, but physical attraction always matters.

"Some people think that's shallow," he said. "That's just the human animal."

SEE ALSO: These are the best ways to improve your online dating profile, according to science

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NOW WATCH: A dating expert reveals an interesting trick for more successful relationships

Clinical psychologist Joseph Burgo Ph.D., author of "The Narcissist You Know," explains the best way to address your significant other's annoying habits in a way that protects the relationship. 

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Like any other annual holiday, Valentine's Day is a chance to reflect on everything that's happened — and all the ways you've grown — in the last year.

In this case, it's an opportunity to consider how your relationship has evolved, and (gulp) whether you think it'll last.

Psychologists have spent years studying the traits that are fundamental to successful long-term relationships and have come up with a few key ideas. We rounded up some of their most surprising insights below.

A word of caution: If you notice that your relationship doesn't meet all these criteria, that does not necessarily mean you should end things with your partner. Consider this list a general set of guidelines that can help you start evaluating whether your current relationship is bringing you satisfaction and happiness.

SEE ALSO: 15 relationship facts everybody should know before getting married

You think about your partner often when you're not together.

In 2007, researchers randomly dialed nearly 300 married people and asked them a series of questions about their relationships and how in love they felt.

Results showed that certain relationship characteristics were linked to stronger feelings of love. One especially interesting finding: The more often people reported thinking about their partner when they were apart, the more in love they felt.

The same study included a follow-up experiment with nearly 400 married New Yorkers, which found that difficulty concentrating on other things while you're thinking about your partner is also linked to strong feelings of love — especially for men.

You respond positively to each other's good news.

Business Insider's Lauren Friedman reported that one litmus test of a happy relationship is how enthusiastically each partner responds to the other's good news.

A Psychology Today blog post breaks down four ways a man could respond after his partner tells him about a promotion at work:

• An active-constructive response from him would be enthusiastic support: "That's great, honey! I knew you could do it, you've been working so hard."

• A passive-constructive response would be understated support — a warm smile and a simple "That's good news."

• An active-destructive response would be a statement that demeaned the event: "Does this mean you are going to be gone working even longer hours now? Are you sure you can handle it?"

• Finally, a passive-destructive response would virtually ignore the good news: "Oh, really? Well you won't believe what happened to me on the drive home today!"

Perhaps unsurprisingly, the response that's most closely linked to relationship satisfaction is the active-constructive response.

You spend some time apart, with your own friends.

Over the past few decades, we've started placing increasing demands on our spouses. As Business Insider's Jessica Orwig reported, no longer do we expect them to be financial partners, protectors, and companions — now we also want them to provide personal fulfillment.

The psychologist who produced some of these findings, Eli Finkel, suggests that if you want to be happy in your marriage, it's best not to look to your partner for all your existential needs. Finkel recommends finding yourself in hobbies, friends, and work.

If there's a good time to reflect on your relationship and where it's headed, it's Valentine's Day.

We've taken this opportunity to round up scientific research on the specific factors that can make or break a romantic relationship.

Below, we've listed 15 nontrivial things you might want to keep in mind before hiring a wedding planner.

SEE ALSO: 10 myths about dating too many people believe

If you wait until you're 23 to commit, you're less likely to get divorced.

A 2014 University of North Carolina at Greensboro study found that American women who cohabitate or get married at age 18 have a 60% divorce rate, but women who wait until 23 to make either of those commitments have a divorce rate around 30%.

"The longer couples waited to make that first serious commitment [cohabitation or marriage], the better their chances for marital success,"The Atlantic reported.

The 'in love' phase lasts about a year.

The honeymoon phase doesn't go on forever.

According to a 2005 study by the University of Pavia in Italy, it lasts about a year. After that, levels of a chemical called "nerve growth factor," which is associated with intense romantic feelings, start to fall.

Helen Fisher, a psychologist and relationship expert, told Business Insider that it's unclear when exactly the "in love" feeling starts to fade, but it does so "for good evolutionary reasons," she said, because "it's very metabolically expensive to spend an awful lot of time just focusing on just one person in that high-anxiety state."

Two people can be compatible — or incompatible — on multiple levels.

Back in the 1950s and '60s, Canadian psychologist Eric Berne introduced a three-tiered model for understanding a person's identity. He found that each of us have three "ego states" operating at once:

• The parent: What you've been taught

• The child: What you have felt

• The adult: What you have learned

When you're in a relationship, you relate on each of those levels:

• The parent: Do you have similar values and beliefs about the world?

• The child: Do you have fun together? Can you be spontaneous? Do you think your partner's hot? Do you like to travel together?

• The adult: Does each person think the other is bright? Are you good at solving problems together?

While having symmetry across all three is ideal, people often get together to "balance each other." For instance, one may be nurturing and the other playful.

Cards in pink and red, candy hearts, and boxes of chocolate line the shelves of stores, waiting to be purchased by lovebirds for their Valentine. 

But if that doesn't describe your current state this year — and you want that to change — we've got you covered. 

In the interest of bolstering your love life, here are some science-backed ways to fall and stay in love:

SEE ALSO: There's now a genetic test for women's fertility called Fertilome

DON'T MISS: Science says couples in lasting relationships typically wait this long to start having sex

For a first date, get coffee, not ice cream.

Yale psychologist John Bargh has conducted a couple of studies that reveal an underlying connection between body temperature and personality.

He found that when we feel warm physically, we also tend to behave more warmly toward others. Therefore, if you want your first date to go smoothly, seek out warm places and foods — they might just help to heat things up later on.

Another first date tip: Be positive.

Contrary to popular belief, men aren't just interested in how you look. That's what a large 2010 study revealed after grouping over 2,100 male university students into three categories. The first group were given photos of women and asked to rate whether they found the women attractive, or not.

Two other groups were provided the photos along with information about the women's personalities — one group had mostly positive personality traits and the other mostly negative. The researchers discovered that the group with mostly positive personality traits found a wider variety of women attractive overall than the other two groups. So, when you're on that first date, just remember to be positive!

Listen up.

This may seem like a no-brainer, but it's actually super critical for all parts of a relationship — at the beginning and when that honeymoon period ends and the inevitable conflicts arise.

A 2010 study of 373 couples from the University of Michigan found that those who were able to discuss issues calmly and listen to their partner when having an argument were less likely to separate later on than couples who didn't do this.

Business Insider also chatted with psychotherapist M. Gary Neuman, who said that listening is key to falling in love because we have a need to be heard.

Relationships come in all sizes and colors — there are romantic relationships, work relationships, and friendships, just to name a few. 

Regardless of what kind of relationship you want to strengthen, each is fundamentally similar to the next in a number of ways.

In all healthy relationships, we are able to listen well, empathize, connect, resolve conflict, and respect others.

The following TED Talks are a great refresher course in doing all that. 

SEE ALSO: A relationship expert explains how successful couples handle their biggest fights

Mandy Len Catron's 'Falling in love is the easy part'

Can you make people fall in love? Twenty years ago, psychologists believed they may have done just that. In their experiment, psychologists had study participants — one heterosexual man and one heterosexual woman — sit face to face and answer 36 increasingly personal questions and then stare silently into each other's eyes for four minutes. Six months later, two of the study participants were married.

"Hoping there was a way to love smarter," writer Mandy Len Catron explored this question in her popular New York Times article, "To Fall in Love With Anyone, Do This," where she chronicles her own experience simulating the experiment and that she did, in fact, fall in love with her partner.

In her TED Talk, Catron explains that the questions, while they may not be entirely responsible for her falling in love, do provide an efficient way for getting to know someone quickly, generating trust, and creating intimacy.

But, more importantly, she says that falling in love is far from the whole story when it comes to loving someone and explains what comes next.

Andrew Solomon's 'Love, no matter what'

Through interviewing parents of exceptional children for several years, the author of "Far From the Tree: Parents, Children, and the Search for Identity" says he has come to understand that everyone is different in some fundamental way, and this core human condition of being different is, ironically, what unites us all.

Solomon explains that all people who love each other struggle to accept each other and grapple with the question, "What's the line between unconditional love and unconditional acceptance?"

Using a number of poignant anecdotes, he helps unpack this question.

Yann Dall'Aglio's 'Love — you're doing it wrong'

Dall'Aglio, a French philosopher and author of "A Rolex at 50: Do you have the right to miss your life?" and "I love you: Is love a has been?," says love is the desire of being desired. But in a world that often favors the self over others, how can people find the tenderness and connection they crave?

It may be easier than you think: "For a couple who is no longer sustained, supportedby the constraints of tradition, I believe that self-mockeryis one of the best means for the relationship to endure," he says.

In this surprisingly convincing talk, Dall'Aglio explains how acknowledging our uselessness could be the key to sustaining healthy relationships.

Why does love lose its intensity over time? appeared as a question on Quora. Below we are republishing an answer from Chloe Shani Malveaux, one of Quora's top writers.

There is a scientific basis for this perception that love is less intense over time. It is because relationships shift from passionate love to long term attachment. Literally if you looked at a picture of your love the first week in the relationship, and then a picture of them 10 years later, you may still love them, but different parts of the brain are being activated and responding depending on where you are in the relationship with that person.

Brain scans have been compared those who were dating for a week to couples who have been together for a year, and they found that the couples who had been together for a year had more activity in the area of the brain associated with long-term attachment.

Infatuation love fades — it is supposed to —but what it also does is it gives the initial push to spend as much time with that person to be able to develop long term attachment to that person by the time the infatuation fades. This is a point where some relationships fail, when the infatuation fades but the attachment never stuck. And people get bored and unsatisfied in the relationship, wondering why they were with the person in the first place. They realize that they no longer love this person anymore because the infatuation love has faded and the long term attachment love never took its place.

But I can see another reason why some relationships fail at this stage is due to our cultural perceptions that infatuation love is true love and it should remain consistent throughout the relationship. That if infatuation love ever wanes then it is an indicator that true love is waning, and therefore the relationship is failing.

In the media, we constantly associate love with infatuation love, since most movies and stories really only cover the beginning of relationships, but when they look at older relationships where the couples are still in love, it seems to imply that it is the same exact infatuation love just diminished in intensity.

Sadly, too many people associate infatuation love as the real deal, when it is only transient. So when people compare their younger relationships to older long term relationships, it isn't like comparing the same things just with two different intensities, it is like comparing apples and oranges.

Quora is the best answer to any question. Ask a question, get a great answer. Learn from experts and get insider knowledge. You can follow Quora on Twitter, Facebook, and Google+.

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It's Valentine's Day, and if you're single, you might be swiping on Tinder.

The app has become one of the world's largest online dating platforms, with an estimated 50 million users. But in 2017 and beyond, it may increasingly have competition.

Although Tinder has a huge user base, other dating apps, like Bumble and Coffee Meets Bagel, are starting to meet a larger percentage of their users' expectations. A recent study looked at user reviews of 97 dating apps and analyzed how their quality scores changed from 2015 to 2016. Of all of the apps in the study, Tinder experienced the largest year-over-year decline.

When users started using Tinder in 2012, every match felt like an adrenaline rush, or at the very least, a spark. However, those matches are no longer quite as novel. They might lead to quick hookups, sleazy come-ons, or nothing at all. That leaves a big opening for Tinder's dating app competitors.

Considered the pioneer of "swiping apps," Tinder's photo-based interface probably contributed to its hookup image. Photos of people nearby pop up, and you swipe right if you like them, left if you don't. When two people swipe right on each other, they "match" and can chat. 

Since Tinder is primarily photo and location-based, it has garnered the perception among users that most of the people on it are looking for sex. This reputation is a boon for newer dating app startups looking to compete with Tinder, like Bumble, Hinge, Happn, Coffee Meets Bagel, Siren, Her— the list goes on.

The main difference between these newer apps and Tinder is that they're not as heavily image-based. They give users the ability to show more of their interests, personality, and identity. Bumble, an app that launched in 2014, is a somewhat popular Tinder competitor with an estimated 800,000 users as of 2015. It has a similar interface as Tinder, but doesn't have the same reputation of being a hookup app. That's because only women can send the first message to their matches on Bumble.

Straight men seem to like the app because women to take more initiative in starting a conversation, as Bryan Bumgardner, a 26-year-old Tinder and Bumble user, explains. He says he has gained more quality matches on Bumble than Tinder, an app he views as primarily for hook ups.

"On Tinder, I can get a dozen matches a night, but most of them are either going to be non-starters, girls who don't respond, weirdos, or people who text back after a month and say 'oh I never check this app,'" he tells Business Insider. But on Bumble, straight women "are assured enough in themselves to pursue a man they want."

Siren, which launched in late 2015, abandons the swipe interface entirely. Only available in Seattle and New York City, it features a daily question and a feed that displays users' answers (the idea being that people's personalities unfold, and you have context for starting conversations). Past questions have included "If you could be invisible for one day, how would you spend it?" and "What was the first album you bought with your own money?"

There are about 35,000 people on Siren so far. Cofounder Susie Lee has told Business Insider that since users don't swipe on Siren, she believes there's less of a sense of objectification. 

"The swiping interaction is fun, but when you apply that to people, you're reducing people to objects. Whether it's shoes or humans, you can do the same interaction: push them away or pull them closer," she said. "We want to fight this idea that you're shopping for humans."

To set themselves apart from Tinder, emerging dating apps are also offering users more ways to describe themselves than just the usual — photos, age, sexual orientation, and a bio. Her, a dating app for LGBTQ women that launched in 2013 and now has 1.5 million users globally, offers those profile options plus more. For instance, it gives 14 options for sexual orientation, 25 for gender, and seven for relationship status. 

If users have the ability to express their true identity, they are more likely to find authentic connections, Her's founder, Robyn Exton, tells BI.

"Being able to express who you really are helps you find people who resonate with that," she says. "Your profile becomes less about 'I’m a lesbian' or 'I’m bi' and more about 'Here’s who I am and what you need to know if you want to go on a date with me.' It lets people express all parts of themselves."

As with Tinder, Her users match with people who have liked their profile. But there's one big difference: the profiles don't disappear once you've swiped.

Michelle, a bisexual 22-year-old, says she migrated to Her from Tinder because the setting on Tinder for "seeking men and women," doesn't yield an even distribution of genders.

"I still see probably 95% men," she says. "And it's really frustrating to feel like my dating app is pushing me to be heteronormative."

Her also wants to be a social network and hosts regular events, something Tinder is exploring with Tinder Social (a feature that encourages groups to meet up).

Michelle adds that Tinder is "primarily for hookups," while Her feels like a community as well as a place for dating. She considers Tinder as more of a confidence-booster, a place to garner matches as physical affirmation.

She also likes Hinge, an app that launched in 2014. Instead of pairing random strangers, Hinge only shows users potential matches who share Facebook friends. Hinge doesn't reveal user numbers, but spokeswoman Jean-Marie McGrath told Vox in 2015 that the app was sparking 35,500 dates per week, and had created 1,500 relationships. 

"It feels like more of a natural connection that you might make in the real world rather than just proximity," Michelle says.

Hinge mimicked Tinder's swipe interface until October 2016, when it relaunched as a paid app with a feed of profiles (which you can "like" and message). When asked about the redesign, Hinge's VP of marketing, Karen Fein, told Select All that "70% of our users are looking for something more serious than free swiping apps offer."

Tinder's reputation as being a place where people only hook-up is, of course, a generalization. People do find relationships and love on the app.

Cosmo recently profiled a number of couples in committed relationships who matched on Tinder. In a 2016 survey by Consumers' Research, 13% of Tinder users reported relationships lasting longer than one month. Tinder doesn't release official statistics around dates and relationships, but says on its site that 26 million matches happen worldwide every day.

In 2015, journalist Nancy Jo Sales wrote a Vanity Fair piece titled, "Tinder and the Dawn of the ‘Dating Apocalypse." In it, Sales talked to young Tinder users at bars, and found that many were using the app to find sex. After, Tinder responded in a series of tweets.

"Tinder users are on Tinder to meet people for all kinds of reasons. Sure, some of them — men and women — want to hook up. But we know from our own survey data that it’s actually a minority of Tinder users," Tinder tweeted at the time. "Our data tells us that the vast majority of Tinder users are looking for meaningful connections."

But the perception problem gives other apps the opportunity to compete with Tinder. None of these apps can rival Tinder's scale yet, but they represent a fresh and varied perspective on online dating. They give daters more options, and that's never a bad thing in the hunt for a partner.

SEE ALSO: What it's like to use Siren, the new dating app that aims to be classier than Tinder

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NOW WATCH: A psychologist explains how to tell if you're ready for a committed relationship

Today, more Americans are choosing to hold off on marriage or forgo it altogether. In 2009, the marriage rate dropped below 50% — for the first time in history.

That stat is highlighted in "All the Single Ladies," a 2016 book by writer Rebecca Traister that chronicles the history of American singlehood. The book features interviews with over 100 unmarried women from a range of socioeconomic backgrounds.

Traister's goal: exploring how social progress connects to changing marriage patterns, and what that means for American single women today.

In addition to companionship, "marriage has been a useful institution for determining power, gender roles, and who does what," Traister told Business Insider when the book launched last year.

Marriage is now just one of many paths women can take. The modern phenomenon of delaying marriage has also transformed marriage itself, Traister said.

Single women, rather than men, play a special role in these changes, because it's now normal to be a thriving single lady. (For the most part, men have always had the option to live independently, she said.)

Here are a few ways marriage is changing for heterosexual couples, according to Traister.

Women hold a higher standard for male partners.

"As more people live independently, marriage means something else for women," Traister said.

Women are no longer dependent on marriage (and men) for economic stability, children, or social support. They can now have all of these things without ever tying the knot. If and when women do marry, they have a higher bar for their male partners, Traister adds.

"It's harder to find a human who is going to make your life better — both economically and emotionally," she said. 

Men are becoming more domestically capable.

Most men have always had the freedom to live independent lives, but if they were married, household duties would often fall to women, Traister said.

Over time, women’s changing responsibilities have also changed men's outlook on their responsibilities, Traister said. Her book points to sociologist Kathleen Gerson’s research, which says that 80% of women and 70% of men "desire egalitarian marriages in which wage earning, domestic duties, and childcare are divided equally."

It's no longer assumed that women will take care of these things.

"If and when men parent, there's a better chance they can hang pictures, cook pasta, vacuum the floors," she said. "And I don't treat that lightly."

Relationships are more equitable.

Sharing laundry responsibilities may seem like a small change, but Traister said an equitable household can translate to a more equitable marriage — and society.

Women are living independently outside of marriage as equals, she said.

"Men and women are now colleagues, or friends going out for a beer — They share music tastes, talk about politics, and have sex without five decades of legal matrimony," Traister said. "We are living in the world as peers."

SEE ALSO: 4 signs a relationship has long-term potential

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NOW WATCH: Here's why you're going to marry the wrong person — and why that's okay

Time spent in bed together is a crucial part of bonding between couples. But if we have trouble getting some shut-eye, this can have a negative impact on our relationships too. 

In a blog post on Psychology Today, marriage consultant Melissa Orlov said many couples slip into patterns that put significant pressure on the health of their relationship.

However, many of these problems can be sorted out easily and quickly as long as you don't ignore them.

It's not just the actual sleeping, either. What you do before bed can have an effect too. Here are some of the bedtime habits couples fall into, which could be having more of a negative impact than they think.

Not getting enough sleep.

According to research by the National Sleep Foundation, the optimum sleep for adults is eight hours a night. Unless you're one of the lucky ones who has different genetics, less than eight hours equals poorer performance. This means it will take you longer to do things, and you won't do them as well.

If you get less sleep, you're also more likely to be irritable with your partner, which can have a negative impact on connections you make with each other in your relationship.

Orlov says to help with this you could start experimenting with things like heavy curtains, drape clips, eye covers, and ear plugs to block out light and sound. LED alarm clocks can also help improve your night's sleep.

Then of course there are night owls and morning larks.

Couples can sometimes be on different schedules. Some people are night owls who stay up later and others are larks who rise earlier in the morning. This can lead to you heading to bed at different times, and waking each other up in the process. 

It might also happen if you're parents, as households may not quieten down until the kids are in bed. In his research, psychologist Dr Jeffrey Larson found that couples whose sleep patterns were mismatched reported significantly less marital adjustment, more conflict, less time spent talking about serious things, less time spent doing activities together, and less sex than matched couples.

Orlov says what you do before bedtime can be key to connecting, as you can chat about your day, and catch up with each other. It's also important to be considerate of each other if you return to the bedroom and your partner is already snoozing. Use a torch instead of turning on the main light and try to be quiet. 

Avoiding or putting off intimacy.

Sex is one of the best ways couples connect with each other, but it can often get forgotten about.

"Many couples I work with are either too caught up with their phones or books, don't feel motivated enough to have sex, or may be 'holding out' on their partner because of unresolved conflict," couples therapist and relationship specialist Melody Li told the Huffington Post.  "Sex itself can be healing to the relationship and can remind partners that they are working together as a team."

Of course, you don't have to get freaky every night to bond. Cuddling has also been shown to help people feel relaxed and happy. 

Valentine's Day practically forces us to assess the success of our relationships. Couples are professing their love left and right, and you might be wondering how you and your partner are doing.

Luckily, research has found that you can simply ask yourself: How much do we laugh together?

Couples who laugh together reported higher quality relationships, according to a study published in Personal Relationships.

The researchers, from the University of North Carolina at Chapel Hill, recorded 71 heterosexual couples telling the story of how they first met. They then counted how many times the couple laughed, and whether they were laughing together or alone.

Couples who laughed together more reported having higher quality relationships, defined by their feelings of closeness and support.

The laughs also exposed some gender differences. Of the nearly 1,400 laughs the researchers recorded, 62% of them came from the women.

But men's laughs were more likely to be contagious, causing their female partner to laugh with them. And this reciprocation had a special effect on the men.

"The greater the duration of shared laughter in the lab, the higher the men's ratings of commitment, satisfaction, and passion toward their partners,"lead study author Laura E. Kurtz, a graduate student, told Business Insider. "These findings suggest that there may be something especially potent about shared laughter for men."

The sample size of 71 couples is too small to know whether there's a similar effect in the general population, but Kurtz said previous research supports this association.

She also told us that she suspects "that shared laughter may play a causal role in promoting [high quality] relationships," though this study showed only a correlation.

Amid all the chocolate, roses, and candlelight this Valentine's Day, make sure there's a hefty dose of laughter, too.

SEE ALSO: Here's how people's sex lives change over the course of a relationship

DON'T MISS: Our minds play a trick on us to keep us from cheating

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NOW WATCH: 7 qualities in men that women find attractive

If you're in your early 20s and Valentine's Day has you thinking about your romantic future, consider the 37% Rule.

According to journalist Brian Christian and cognitive scientist Tom Griffiths, coauthors of "Algorithms to Live By: The Computer Science of Human Decisions," that rule could help you save time looking for a spouse.

The 37% Rule basically says that when you need to screen a range of options in a limited amount of time — be they candidates for a job, new apartments, or potential romantic partners — the best time to make a decision is when you've looked at 37% of those options.

At that point in a selection process, you'll have gathered enough information to make an informed decision, but you won't have wasted too much time looking at more options than necessary. At the 37% mark, you're in a good place to pick the best of the bunch.

A common thought experiment to demonstrate this theory — developed by non-PC math guys in the 1960s — is called "The Secretary Problem."

In the hypothetical scenario, you can only screen secretaries once. If you reject a candidate, you can't go back and hire them later (since they might have accepted another job). The question is: How deep into the pool of applicants do you go to maximize your chance of finding the best one?

If you interview just three applicants, the authors explain, your best bet is making a decision based on the strength of the second candidate. If she's better than the first, you hire her. If she's not, you wait. If you have five applicants, you wait until the third to start judging.

So if you're looking for love between the ages of 18 and 40, the optimal age to start seriously considering your future husband or wife is just past your 26th birthday (37% into the 22-year span). Before then, you'll probably miss out on higher-quality partners that could still come around, but after that, good options could start to become unavailable, decreasing your chances of finding a good match.

In mathematics lingo, searching for a potential mate is known as an "optimal stopping problem." Over 1,000 possibilities, Christian and Griffiths explain, you should pull the trigger on someone 36.81% of the way through. The bigger the pool of options, the closer to exactly 37% you can get.

Research about successful marriages seems to support the age sweet spot of 26.

In July 2015, the University of Utah sociologist Nicholas H. Wolfinger discovered that the best ages to get married in order to avoid divorce are between 28 and 32. The range doesn't align exactly — 28 years old is closer to a 45% Rule — but partners usually decide on each other a while before their actual wedding. Wolfinger's analysis also revealed that a couple's chances of breaking up increased by 5% each year after age 32.

The 37% Rule isn't perfect. Since it borrows from the cold logic of math, it assumes that people have a reasonable understanding of what they want in a partner by 26, but doesn't account for the fact that what we look for in our partners may change dramatically between 18 and 40.

What the 37% Rule does tell us is that 26 is the age when our dating decisions are most trustworthy— it's the point at which we can stop looking and start taking those big leaps of faith.

SEE ALSO: Americans are staying single longer than ever, and it’s changing modern marriage in 3 major ways

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It's Valentine's Day, which might be a reminder of just how confusing dating in the 21st century can feel for some. We have complicated ways of connecting that didn't exist 20 years ago, and many of our conversations with romantic partners happen via text message.

Comedian Aziz Ansari has a lot to say about this. In his first book, "Modern Romance," Ansari worked with sociologist Eric Klinenberg to explore how we date in the digital age. They talked to hundreds of single people across the world, asking how they connected with romantic partners.

Ansari and Klinenberg discovered that the culture of finding love had evolved dramatically, fueled in part by the invention of cellphones and the explosion in online dating.

They also found that a lot of people had questions about texting etiquette.

Here are some of their tips from the 2016 book.

Don't wait to send that first text

Though the three-day rule has floated around as solid advice for what seems like forever, Ansari and Klinenberg found it to be a myth.

After you meet someone you like, they concluded, the best time to send the first text is that same day. Touching base sooner rather than later keeps the romantic momentum going.

That person already gave you his or her number, so there's a good chance the person digs you.

Avoid 'heyyy' and make it personal

Ansari and Klinenberg found one of women's most common texting peeves was the generic "hello" text.

"After seeing hundreds and hundreds of messages in women's phones," Ansari writes, "I can definitively say that most of the texts women receive are, sadly, utterly lacking in either thought or personality."

Instead, mention something you talked about when you first met that person. Show the person you actually listen to what he or she says.

Try to be clever

Adding a dose of comedy to your texts can really up your game, Ansari says. It keeps things lighthearted and makes you memorable to the other person.

At the same time, try not to overdo it, because sarcasm or offbeat humor can be hard to decipher over text.

Text at normal hours

It's best to text in the afternoon or evening and not early in the morning or late at night, Ansari and Klinenberg say. Otherwise, you run the risk of waking the person up.

Don't text back immediately, but don't overthink your response time

In their focus groups, Ansari and Klinenberg found that generally you shouldn't text someone back right away. Texting back immediately apparently gives off the vibe that you're too eager or desperate.

Waiting an hour or two will make you seem more desirable because it shows that you have other things going on in your life. That said, don't wait too long, which could show a lack of interest.

Use correct grammar and spelling

"Plz" and "Idk" may be OK in texts with friends, but Ansari and Klinenberg say you're better off using proper English with your crush.

Bad grammar was a major turnoff in almost every focus group. Texting things like "Hey we shud hang out sumtimez" make the sender seem unintelligent and lazy.

Make concrete plans

Ansari suggests avoiding the generic "What's up?" or "Want to hang?" texts. Instead, be forward and direct.

Invite your crush to do something specific at a specific time. It shows that you're interested in actually spending time with the person, rather than just penciling him or her into your schedule.

Get to know them in person

Sending a slew of texts isn't a substitute for actually getting to know someone IRL (in real life), Ansari says.

When you do plan that first date, he recommends following what he dubs the "Monster Truck Rally Theory." Don't take your date out to a mundane place like a coffee shop or a restaurant — go somewhere exciting like, say, a monster-truck rally. An interesting date helps you see what it's really like to be with a person.

"Don't just stare at each other across the table while sipping a beverage and making the same small talk you've made a thousand times about siblings, hometowns, and where you went to college," Ansari writes. "A person may seem just okay, but if you really invest time in the relationship, maybe they'll be greater than you assume."

SEE ALSO: Americans are staying single longer than ever, and it’s changing modern marriage in 3 major ways

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Romantic love is shrouded in mystery. What draws people together and how does the falling-in-love process work?

According to Elizabeth Philips, a research psychologist and expert in human-robot interaction, there's actually a fair amount of science that helps explain the phenomenon. Psychologists have identified ten factors that explain why and how we fall in love. 

Here are some of the factors that can play a role:

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Right on time for Valentine's Day, Spotify has released a list of the best songs to make love to. These are not the best "love songs," mind you, but the best ones for the bedroom in particular. 

To find the top tracks, Spotify's data scientists looked through the "sex" playlists on its service to see which songs were streamed most frequently. Spotify also did this last year, and the one common denominator was that The Weeknd charted both years, which is, honestly, a tad concerning. Stay emotionally healthy everyone!

But without further ado, here are the top 10 for 2017:

1. "Sex With Me"— Rihanna
2. "Birthday Sex"— Jeremih 
3. "Ride"— SoMo 
4. "Earned It" (Fifty Shades Of Grey) — The Weeknd
5. "Slow Motion"— Trey Songz 
6. "Often"— The Weeknd
7. "Neighbors Know My Name"— Trey Songz
8. "Pony"— Ginuwine
9. "Sex"— Cheat Codes
10. "All The Time"— Jeremih 

And here were the top 10 for 2016:

1. “Don’t” – Bryson Tiller
2. “Marvins Room” – Drake
3. “The Morning” – The Weeknd
4. “Or Nah” (featuring the Weeknd, Wiz Khalifa and DJ Mustard) – Ty Dolla $ign
5. “Lotus Flower Bomb” (featuring Miguel) – Wale
6. “L$D” – A$AP Rocky
7. “Crew Love”– Drake
8. “Sorry” – Rick Ross
9. “Swimming Pools” (Drank) – Kendrick Lamar
10. “Love Yourz” – J. Cole

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Happy Valentine's Day!

If you're eating heart-shaped chocolates alone in a bathrobe this Tuesday, don't worry: Society doesn't get to tell you the right way to celebrate the life of a martyred third-century Catholic saint — and also, love and attraction are weird and mysterious things.

There's a lot we don't understand about love — to the degree that we're even sure it exists as a meaningful psychological state outside of social constructs. And there's a lot that's idiosyncratic to individual people and couples.

That's why a lot of research into why we mate is bizarre to the point of incoherence — cultural norms as well as oddities in research methods can create a lot of noise. Yet it turns out there is a lot of science about why people fall in love that is at once super strange and actually fairly credible.

Keep in mind that no one study is enough to draw definite, broad conclusions. That's especially true because this research tends to focus on the specific behaviors of heterosexual undergraduate students at the universities where researchers work.

Still, there's a lot of fascinating knowledge out there about our habits of love and attraction.

Here are nine of the most interesting findings:

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1. People tend to fall in love with other people who are like them. Shared values, life experiences, levels of attractiveness, and age can all make a major difference.

Sources: Journal of Experimental Social Psychology, Journal of Personality and Social Psychology, Journal of Personality and Social Psychology

2. If you want someone to fall in love with you, then it might help to resemble their opposite-sex parent. That can mean hair and eye color but also age. Children of young parents tend to seek out young partners more often.

Source: Evolution & Human Behavior

3. There's some evidence that scent can play a role in attraction. Ovulating women, for example, may prefer the scents of men with more testosterone. And men may prefer the scents of women at certain times in their menstrual cycles.

Sources: Proceedings of the Royal Society B, Psychological Science, Psychological Science

Also, check out our review of a site that matches people based on how they smell after not showering.

Anyone who's been through a bad breakup has experienced the symptoms: talking about it incessantly to friends, obsessively checking an ex's social media posts, or trying to run into them accidentally on purpose.

But Mend, an app that aims to be a "personal trainer for heartbreak," wants to help you avoid those mistakes and move forward with your life.

Ellen Huerta created the app after going through a breakup herself, according to The New York Times. Huerta is more than the founder, though — she is also Elle, the soothing voice within the app that guides you through your breakup.

Mend isn't just a breakup coach; it's an entire community for the brokenhearted. Here's how it works.

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Huerta, a former Googler, originally founded Mend as a newsletter about moving on from a breakup. Huerta told The Times that she hopes to "erase the shame and taboo of heartbreak as something to just get over."

Source: The New York Times

Mend doesn't want to be just a breakup app. It wants to be a community for the heartbroken — and that doesn't apply only to women. Everything on the app is gender-neutral and doesn't assume your relationship was heterosexual. Your previous partner is referred to simply as "your ex" throughout the app.

To get set up, all you have to do is enter your first name. You can make a Mend account, but it's possible to skip that step.

One important feature to note is the "Is this an emergency?" button. Clicking that takes you to a page that explains that Mend is not a substitute for mental health services and urges you to seek professional help if it's more serious than run-of-the-mill sadness.

Many people say they want their romantic partner to have a great sense of humor, but eHarmony CEO Grant Langston thinks he can do better: He wants to know exactly which kinds of humor people prefer.

"Human beings think sense of humor matters," Langston tells Business Insider. "We're trying to find out if it does matter. We're trying to type people for humor."

People who can quote every joke in "Airplane!" may not be the same people who laugh at cartoons in the New Yorker or enjoy a good fart joke. To address those comedic nuances, eHarmony is currently conducting research that the company intends to incorporate into its matchmaking algorithm.

That research has identified nine distinct categories of humor: physical, self-deprecating, surreal, improvisational, witty, topical, observational, bodily, and dark. Over the next several months, eHarmony will test the theory that people with similar senses of humor will enjoy richer, stronger relationships.

The company has performed two studies to test that model so far, with three more in the pipeline. In the studies, participants are given a couple dozen video clips to watch, each about 30 seconds long. They include skits from "Whose Line Is It Anyway?", stand-up comedy, viral Internet prank videos, and more. People rate how funny each is along the way.

The final product: an individualized sense of humor web, with each category scored out of five possible points depending on how funny a given person rated each clip.

Langston sent me the test — I scored a 5 on witty, self-deprecating, and bodily, and a 1 on surreal. The others fell somewhere in between.

In the lab studies, participants who'd taken the humor test were then set up on a handful of 10-minute speed dates. At the end, they noted which people they'd like to see again. To figure out what role humor plays in romantic chemistry, Langston and his team will see how much overlap there is between people who matched in humor types and those who matched in the speed dates.

"At this point, it seems very likely that it will be an important way to match people," Langston says, but adds that isn't the final step. "You have to ask yourself, Does it correlate to better relationships?"

That remains to be seen, since eHarmony has yet to roll out the system in its actual service. Langston says he's still figuring out the best way to integrate that video-watching into the existing onboarding process. People may be perfectly happy to take 15 minutes out of their day to watch random Internet videos — or they may not.

At the very least, Langston says, people do want partners who like to laugh, and it's worth seeing whether they'll like them more if they find the same dumb joke or witty retort equally funny.

"It's easy to see that if you're a certain humor profile and this person is a certain humor profile, I want you guys to meet each other," he says. Langston acknowledges, however, that common interests are still important. "If your compatibility is also good, then that is a home run for us."

SEE ALSO: The 3 biggest mistakes people make in online dating, according to the CEO of eHarmony

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Love and work — who knew the two were so intimately connected? Based on research by Bloomberg Business, it turns out that your job could help you predict who you'll end up marrying.

By scanning US Census Bureau data covering 3.5 million households, Bloomberg compiled this interactive chart that shows how people are pairing up by profession.

Here are the most common matchups for 35 jobs (Some opposite-sex matchups weren't common enough to make the list):

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Elementary- and middle-school teachers

Female elementary-school teachers are most likely to marry male or female elementary- and middle-school teachers.

Male elementary-school teachers are most likely to marry female elementary- and middle-school teachers or male education administrators.

Financial analysts

Female financial analysts are most likely to marry male financial managers or female retail salespeople.

Male financial analysts are most likely to marry female elementary- and middle-school teachers or male operations research analysts.

Flight attendants

Female flight attendants are most likely to marry male managers or female flight attendants.

Male flight attendants are most likely to marry female flight attendants or male elementary- and middle-school teachers.